Abstract

IRI 2001 model prediction is compared to custom orthotic design group total electron content (CODG TEC) maps prediction at Niamey during several geomagnetic (quiet, fluctuating and shock days) conditions for the period of IHY campaign. Independently of geomagnetic conditions, the qualitative comparison between CODG TEC maps and IRI 2001 TEC shows the overestimation of IRI 2001 model. The overestimation of CODG TEC maps at Niamey by IRI model is also shown by examining quantitative methods (relative deviation module means (rdmm) and percentage deviation) results. The quality of IRI prediction, that is, the amplitude of estimation depends on geomagnetic condition and month. In fact, rdmm values of March and April for quiet day periods respectively are 0.53 and 0.41. During fluctuating period, rdmm values are 0.35 in March and 0.39 in April. When act CMEs, rdmm value is 0.67; thus the work shows on one hand the necessity to improve IRI model and on the other hand to study the effect of each disturb solar event separately.

Key words: Total electron content, custom orthotic design group, international reference ionosphere, geomagnetic classes of activity, relative deviation module means, percentage deviation, concordance.